Showing papers in "Aerospace Science and Technology in 2004"

TL;DR: Using Kalman filtering theory, a new multi-sensor optimal information fusion algorithm weighted by matrices is presented in the linear minimum variance sense, which is equivalent to the maximum likelihood fusion algorithm under the assumption of normal distributions.

TL;DR: In this paper, the concept of additive throughflow drag is introduced, and the analysis of jet-propelled transonic transport aircraft on the basis of calculated viscous flow is discussed.

TL;DR: A review of active methods for controlling supersonic flow around bodies: propagation of sound and shock waves in weakly ionized gases and anomalous changes reported in the drag of bodies moving through such gases; "electrodynamic action" on the flow for decreasing sonic-boom intensity; counterflow injection of plasma jets and chemically active gas for drag reduction as mentioned in this paper.

TL;DR: In this article, the authors showed that active control using oscillatory flow excitation can effectively delay flow separation from, and reattach separated flow to, aerodynamic surfaces at various flight conditions.

TL;DR: It is shown in hardware-in-the-loop tests and in a test drive that processing time differenced carrier phase measurements instead of delta-range measurements results in an increased velocity and attitude accuracy for the tightly coupled system, which is of great importance in the beginning of a time interval with purely inertial navigation.

TL;DR: In this paper, the results were compared with HTPB propellants containing iron (III) oxide as catalysts and the results showed that the higher burning rate values were obtained with samples which presented a more defined crystalline shape, i.e., the ones synthesized by the coprecipitation method.

TL;DR: In this article, the authors describe the results of an effort on the modeling of the UAV aerial refueling problem and on the design of the docking control scheme based on a fuzzy sensor fusion strategy featuring GPS and Machine Vision (MV) data.

TL;DR: In this paper, the rotor wake was intensively measured with a double-stereo PIV (Particle Image Velocimetry) system, which provided instantaneous flow field data in both a large observation area and in a smaller close-up view to the vortex core.

TL;DR: In this article, the authors present a study that was carried out within the European sponsored project CRYOPLANE, co-ordinated by Airbus Germany to evaluate the environmental impact of the use of cryoprocessors in medium-range aircraft.

TL;DR: In this paper, the potential of the adjoint technique for aerodynamic shape optimization is described, and specific requirements for an optimisation framework combined with the Adjoint technique are introduced, where the drag reduction at constant lift and pitching moment for the RAE2822 airfoil in transonic flow is evaluated.

TL;DR: In this paper, the authors compared the performance of Kirchhoff and Fowcs Williams and Hawkings (FW-H) surface integral methods from a theoretical and practical point of view.

TL;DR: In this article, a quasi-steady approximation to modeling rotors with actuator discs is presented, which reduces the cost of an unsteady simulation down to a stationary one.

TL;DR: The electrostatic space accelerometers mounted on board the three satellites of the two last geodesy missions, CHAMP and GRACE, respectively launched in 2000 and 2002, take continuous and accurate measurements of the satellite drag acceleration.

TL;DR: In this article, a distributed horse-shoe technique is used to model the aerodynamic effects of formation flight, such as changes in lift and drag forces and lateral/directional effects that do not appear in a steady-level "isolated" flight.

TL;DR: In this paper, the authors investigated the influence of low visibility conditions, especially fog, for air traffic during landing approaches and found out whether the use of IR cameras for an EVS can improve the visibility at defined conditions of ICAO standard visual range categories CAT I, II, IIIa and IIIc for landing approaches.

TL;DR: In this paper, a methodology called Vortex Encounter Severity Assessment (VESA) is proposed to assess the severity of a wake vortex encounter (WVE) during landing approach, which makes it possible to compare the effect of wake vortices generated by different aircraft on an aircraft that encounters a vortex.

TL;DR: In this paper, the use of multiple active trailing edge flaps for vibration reduction in a helicopter rotor was investigated using an optimization approach, and it was shown that using upto four flaps at the blade tip (outer 20%) is optimal for reducing vibration with reasonably low control angle deflections and therefore low power requirements.

TL;DR: In this article, a nonlinear output feedback control system for the stabilization of an aeroelastic system with structural nonlinearities is presented, based on a backstepping design technique, and a control law for the trajectory control of the output variable is derived.

TL;DR: The European PartEmis project as discussed by the authors has been used for the characterization and quantification of emissions of aerosols and gaseous precursors from a gas turbine engine with a 3-shaft turbine.

TL;DR: In this article, a pre-design of a solar-hydrogen energy system was carried out for an airship (volume 580,000 m3) withstanding continous wind speeds up to ≈130 km/h.

TL;DR: In this paper, the non-steady internal ballistics of a star-grain solid-propellant rocket motor are investigated through a numerical simulation model that incorporates both the internal flow and surrounding structure.

TL;DR: In this paper, a multi-level approach has been used in order to break down the problem into several sub-problems taking into account the structural coupling effects, which enables the use of parallel computer processing leading to a significant reduction of the computer run time and decreases the design cycle time.

TL;DR: Beihang Univ, Sch Automat Sci & Elect Engn, Beijing 100083, Peoples R China.

TL;DR: An on-board architecture designed to enable an unmanned aerial vehicle to carry out an observation mission autonomously and to manage the course of the mission is presented, based on a Petri net formalism.

TL;DR: In this paper, an adaptive neural control concept for the deployment of a tethered re-entry capsule is presented, which applies an indirect neural controller that combines two neural networks, a controller network and a plant model network.

TL;DR: In this paper, a predictive control for the attitude maneuver of a flexible spacecraft model is proposed, which takes the flexibility into account which is caused by the rotational maneuver of spacecraft body.

TL;DR: Approximate cruise range solutions are introduced for the constant altitude – constant high subsonic speed flight of turbojet/fan transport aircraft with cambered wing design for estimation of the cruise range of aircraft during conceptual or preliminary design phase.

TL;DR: In this paper, a numerical investigation of active flow control, which can offer significant improvements to aircraft wing, helicopter and wind-turbine rotor performance by suppressing detrimental effects of separated flow, is presented.

TL;DR: In this article, the authors present a graph-theoretic approach for the automatic derivation of the solution path of the conceptual system design equations, which simplifies the study of the couplings between system design parameters and helps to automate the desired sensitivity analysis.